The invention is useful in the field of plant containers that automatically water the plants growing therein with just enough water, the amount of water being self-regulated by the degree of dryness near the rootball of the plant by a hydrophilic sensor.
The urban and suburban nature of modern living has led to a proliferation in the use of potted plants as decorative items. Living potted plants are commonly found in private homes, restaurants, hotels, office buildings and many other locations. Consequently, devices for containing and caring for potted plants have become a major commodity.
One of the most desirable types of potted plant devices available is the self watering planter. Self watering planters are devices containing relatively large water or fluid reservoirs which may be periodically filled and which then dispense the water to the plant as the plant requires it. Self watering planters have been devised to operate by way of timer systems or by way of constant low volume seepage into the soil surrounding the plant. One of the most effective self watering planters, however, is the type wherein a sensor is placed within the soil of the plant to sense the level of moisture in the soil and cause additional water to be delivered to the soil if the moisture level is too low. Sensing self watering planters of this type have utilized electrical sensing units, an expensive and possibly dangerous solution, and porous hydrophilic (water loving) sensors.
In the discussion which follows there is described a self-regulated automatic watering planter described in a U.S. Pat. No. (4,329,815) which is believed by the applicants to be the closest prior art. This planter uses a porous hydrophilic sensor to provide automatic watering by sensing the water content in the soil.
Porous hyrophilic sensing devices allow air to pass through the porous material when it is dry but prohibit the passage of air when the porous material is wet. The porous sensor is connected to an air-tight water reservoir such that when the sensor is blocked by water, atmospheric pressure cannot reach the water reservoir and vacuum pressure prevents the delivery of water to the soil of the plant.
The invention claimed herein is an improvement on this technology using the same principle of operation but improved structure. Since the easiest and clearest way to define the genus of self-regulating, automatic watering planters which the claims are intended to cover is by comparison and contrast with the planter described in U.S. Pat. No. 4,329,815, the background art and summary of the invention sections have been combined into one section for purposes of this patent application.
U.S. Pat. No. 4,329,815 to Secrest, filed Nov. 7, 1980, which is hereby incorporated by reference, represents the predecessor product to the invention described herein and works on the same scientific principles as the invention. The term "self-regulated automatic watering planter" as used in the claims means a self watering planter identical in principal in operation to the planter defined in U.S. Pat. No. 4,329,815 but not needing absolutely every physical characteristic of the planter described in that patent. The features which are not necessary to be included in a claimed structure using the term "self-regulated automatic watering planter" will be specifically identified in the below given discussion of the structure of the planter defined in the '815 patent.
The '815 patent teaches a plant container having an outer shell 14 and an inner shell 12 with substantially vertical walls (vertical walls are not required in the claimed planters where the claim uses the term "self-regulated automatic watering planter") which are concentric and which are sized so as to form a concentric water reservoir which is sealed against the atmosphere. In the '815 patent planter, the outer and inner shell are welded together at the top to form a composite structure. This is done by welding a rim 15 which projects outward from the top of the wall formed by the inner shell 12 to the top edge of the wall of the outer shell 14. In the planters claimed herein using the phrase "self-regulated automatic watering planter", welding of the inner shell and outer shell together at the top is not necessary. The inner shell has a ridge at the top of its wall which extends outward toward the top of the outer shell wall. The underside of the ridge has two downward extending ridges which are spaced apart and which have inner walls with grooves or detents formed therein. The top of the wall of the outer shell has two beads formed on the outer and inner surface at the top of the wall. The top of the wall of the outer shell snaps into the space between the two downward extending ridges when the beads engage the groove or detents. In some species this snap fit is tight enough to be airtight. if the snap fit is adequately tight to make an airtight seal at the top of the reservoir, no further welding or sealing is necessary. However, if the snap fit is not tight enough to make an airtight fit, the seam between the inner and outer shell must be sealed so as to be airtight since an airtight seal is necessary to the proper operation of the invention. In the preferred species, this is accomplished with a bead of glue.
In planters in the genus of the invention, the inner shell and outer shell do not need to be welded together to form a mechanical bond as that mechanical connection is formed by a snap fit which will be described in greater detail in the detailed description of the invention section. However, as noted above, there must be an airtight seal.
In the '815 patent planter, the water is stored in both the space between the walls of the inner and outer shells and in the space between a "substantially flat" bottom wall supporting the soil in the planter and a second bottom wall comprising part of the outer shell. In any claimed invention herein where the phrase "self-regulated automatic watering planter" is used, it is not necessary that the walls be concentric or round or that the water be stored all the way around the circumference of the planter or that the bottom wall be substantially flat. In fact, in the preferred embodiment of the invention, the bottom wall is flat on the outside perimeter but has a circular well centered therein wherein the bottom wall of the well has the holes which allow passage of water from the reservoir into the soil. Unlike the inlet port in the '815 patent which is plugged by an inlet filter, the inlet ports in the "self-regulated automatic watering planter" do not use inlet filters at all and have a shape like an inverted funnel so as to provide a venturi effect. The venturi effect converts the pressure of the water entering the wide mouth of the opening into higher velocity as the water goes through the more narrow mouth of the opening leading to the soil. This acceleration of the water helps the keep the holes unplugged and eliminates the need for a filter.
It is necessary in all species within the genus of self-regulating, automatic watering planters claimed herein that the water reservoir have some height so as provide some hydrostatic head pressure to drive the water up through the passageways in the bottom of the well when the hydrophilic sensor is dry, and it is necessary that the tube connected to the hydrophilic sensor be coupled into the air space at the top of the reservoir so as to selectively couple and decouple atmospheric pressure to the air space above the water, i.e., the hydrophilic sensor acts as a valve between the atmosphere and the vacuum space above the water level in the reservoir. The hydrophilic sensor valve is open when the sensor material is dry and closed when it is wet. It is also desirable to either locate the air tube opening above the level of the fill tube opening to prevent backflow of water into the air tube or use any other means such a filter impermeable to water but permeable to air at the inlet of the air tube to prevent it from being filled with water. The '815 patent teaches use of heat shrink tubing to couple the air tube to the sensor, but in the genus of the invention this method as well as other methods such a glue or tight interference fits may also be used so long as the permeability to air is not affected.
In the '815 patent planter, a niche in the ridge at the top of the inner shell's ridge is formed to make a spot for the fluid fill port. In the genus of the invention, the niche is not necessary, and it is only necessary that there be a fill port which can be used to fill the reservoir and which can be plugged by a stopper to be airtight. In alternative embodiments, the fill port may be a valved port.
In the '815 patent planter, there are passageways at the bottom of the reservoir which lead to the soil in the container through an input filter. The input filter is comprised of a porous hydrophilic material. The input filter acts as a baffle to slow the flow of water into the soil when the vacuum is broken (atmospheric pressure is coupled to vacuum space above water level in reservoir). This filter had a tendency to clog up about every 4-5 years with silt and cause the planter of the '815 patent to cease functioning because the water could not pass the inlet filter. The filter had to be replaced which required that the entire plant had to be removed to gain access and change the filter. While this was not a big job, it was inconvenient and could also cause plants to die if the attendant did not notice within a reasonable time that the planter was no longer automatically watering. In planters claimed herein using the phrase "self-regulated automatic watering planter", this input filter is not included in the structure intended to be indicated by that phrase.
In the '815 patent planter, the inlet port is surrounded by a broken annular ridge 26 which was raised above the bottom wall or floor 18. The broken annular ridge was inside a concentric annular ridge 28 which is higher. Neither of these ridges is included within the planter indicated by the phrase "self-regulated automatic watering planter" used in the claims.
The top of the reservoir in the '815 patent planter is coupled to a hydrophillic sensor 37. This sensor is coupled in an airtight fashion to the airspace at the top of the reservoir by a tube in the form of a hollow, flexible plastic tube. This tube has the sensor blocking one end, and is long enough to extend from an airtight port at the top of the reservoir into which the tube is inserted to a location somewhere beneath the top surface of the soil in the container, preferably about 1/3 of the way down the rootball. The sensor is a hydrophilic material. It is impermeable to air when moist. When there is enough water in the soil, the sensor absorbs moisture, preventing air from passing through the sensor thereby sealing the reservoir off from the atmosphere. When the top of the reservoir is sealed to the atmosphere, water in the reservoir will wick into the soil only to the extent that the drop in the water level in the reservoir creates a vacuum of sufficient level to prevent further water from entering the soil.
As the soil drys out from evaporation, the hydrophilic sensor material drys out as well and becomes porous enough to allow air to pass therethrough. When this happens, the vacuum is dissipated enough to let further water move by hydrostatic pressure and capillary action into the soil through the inlet filter to replace the evaporated water. The soil then becomes moist thereby causing the hydrophilic material to absorb moisture and become impermeable to air again thereby sealing the reservoir off from the atmosphere. The water continues to move into the soil until the water level drops enough in the reservoir to again create sufficient vacuum to prevent further water from moving into the soil. This cycle repeats itself every time the soil becomes dry enough for the hydrophilic material to allow air to pass therethrough. In the genus of the invention, the same type of hydrophilic sensor self-regulation is used, and the sensor of the '815 patent may be used. The '815 patent uses a hydrophilic sensor of sintered polyethylene which has been coated with a surfactant that makes it hydrophilic. The preferred average pore size of the polyethylene material is 20-30 microns. The sintering is conducted after the surfactant is applied to the polyethylene to create the desired pore size but the sintering also results in the surfactant staying on the polyethylene longer.
The '815 patent planter teaches radial baffle fins 48 extending outward from the center of the bottom portion of the outer shell and a slope-sided nipple element 50. These baffles and nipple element serve to prevent fouling of inlet filter by impeding progress of floating debris in the reservoir toward the inlet filter. The '815 patented planter also teaches a floating debris guard 52 in the form of an annular ring which restricts floating debris from reaching the inlet port. None of these baffle, nipple or floating debris guard elements is required in the "self-regulated automatic watering planters" of the genus of the invention although they can be used in some species. The preferred species uses a well in the bottom of the inner shell the bottom of which very closely approaches the upper surface of a flat bottom wall of the outer shell. While the distance between the bottom of the well and the flat bottom wall of the outer shell is sufficient to let water pass, larger floating objects are impeded from reaching the inlet holes by the narrow passageway.
The '815 patent also teaches a root barrier structure which is described in the following way:
In the device 10, it may be noted that the inlet filter 22 and washer 24 are recessed downward from the bottom surface 18 of bowl 16 in inlet port 20. Situated directly above the inlet port 20 is the thin circular disk 30 which rests upon broken annular ridge 26. The thickness of disk 30 combined with the depth of broken annular ridge 26 is approximately equal to the depth of solid annular ridge 28. Thus, the upper surface of disk 30 is level with the upper surface of solid ridge 28. The exterior edge of disk 30 extends almost to the interior edge of solid ridge 28 to form therebetween an annular fluid aperture 54. Annular fluid aperture 54 provides the route by which water or other fluid is delivered to the interior of bowl 16 and consequently to the plant.
Basically, this root barrier is a thin disk resting on top of the broken ring and having a diameter just a little smaller than the diameter of the solid annular ridge 28. This provides a path for water travelling upward but not enough space for roots travelling downward toward the inlet filter so as to be able to clog it. This exact root barrier structure from the '815 patent is not necessary in the genus of the invention, but another root barrier is used in the preferrred species. This new root barrier structure is comprised of a patch of Bioguard.TM. root barrier fabric placed over the inlet holes. This root barrier fabric has time release nodules of nonwater soluble herbicide attached to the fibers of the fabric. The herbicide stays near the fabric and is not carried by the water up to the root ball. Any roots that get close to the inlet holes are suppressed by the herbicide.
A self watering planter using a porous hydrophilic sensor is described in U.S. Pat. No. 3,758,987 issued to W. Crane, Jr. The Crane patent discloses a self watering planter having the inlet port to the soil located at the center of the bottom interior of the planter. In a device of this construction, the water enters the soil from the bottom while the sensor measures the moisture content of the soil near the top. When the moisture level at the sensor element is sufficiently high to block the pores such that air may no longer flow through the sensor element, the water flow into the soil is stopped.
Another type of self-watering plant container is available in the prior art. These types of containers are commercially available from Jardinier of Costa Mesa, Calif. This second type is a wicking type container with no self-regulating feature. These type planters are simply pots with holes in the bottom which lead to a water reservoir below. The water reservoir is not sealed to the atmosphere and there is no hollow flexible tube which extends from a port in the reservoir into the soil with the end thereof blocked by a plug of hydrophilic material. These types of containers therefore allow water to wick into the soil at whatever rate the soil will absorb the water and the degree of water saturation in the soil is solely a function of the water absorption capability of the soil and not a function of how much water the plant needs.
In contrast, the self-regulating, self watering type containers meter the amount of water that goes into the soil by virtue of the pore size of the hydrophilic material. Typically, pore sizes of 30 microns have been found to work satisfactorily to control the amount of water that gets into the soil to a healthy amount for the plant.
The advantages of these self-regulating, self-watering planters are several. First, they take away the need for botanically sophisticated technicians who are able to decide how much water a plant needs and visit the plant often enough to make sure its soil's water content is just right. Second, they reduce the cost of plant losses to plant maintenance and client companies which use them since fewer plants die from too much or too little water.
These type of self-watering plant containers are favored by plant maintenance companies. Typically, industrial companies contract with plant maintenance companies to take care of plants in the buildings of the company. The plant maintenance companies may sell the plants and containers to the client companies or lease them. Frequently, decorative planters are used which are simply for aesthetic appeal with the actual plants being contained in plastic planters that fit within the decorative planters.
The assignee of the present invention offers decorative planters that have built in self-regulating, automatic-watering capabilities. However, these decorative planters are more expensive than decorative planters without self-regulating, automatic-watering capabilities. The higher price of the prior art self-regulating, automatic-watering planters such as are taught in the '815 patent chills sales when competing with the cheaper continuous watering planters with no hydrophilic sensor technology.
Further, the continuous watering planters with no hydrophilic sensor technology have thinner walls since most or all of the water in the reservoir is stored beneath the floor of the inner shell. As such, they fit well into existing decorative planters which have dimensions designed to fit these planters. In contrast, the planters taught in the '815 patent have dimensions which do not fit in decorative planters already in the hands of plant maintenance companies.
When client companies or plant maintenance companies already have decorative planters, it is difficult to sell them decorative planters with self-regulating, self-watering capabilities that do not fit within their existing decorative planters since the client is hesitant to scrap perfectly good decorative planters.
When client companies or plant maintenance companies do not already have decorative planters, they prefer to buy a combination of decorative planter and and self-regulating, automatic watering planter that fits perfectly in the decorative planter and which is priced competitively with self watering planters which are not self-regulated.
Therefore, a need has arisen for a self-regulating, automatic watering planter which is cheaper to build and at least some species of which can fit properly in existing decorative planters.